help with mercruiser 5.0L !

[slothman]

I need help with my 95 mercruiser 5.0L . Took her out today and it would not start in the water. Took it out of the water, cranked it a few more times, she started and idled. put her back in the water, started, idled out 500 yards. The she sputtered and died, almost like loss of fuel.

I have read that the oil pressure switch can fail, and cause the fuel pump not to run. I think this might be the issue. I found a switch, right about the oil filter. It has one single wire, blue with orange. I believe this is the oil pressure switch, but I am not sure. I looked in the merc parts, and found part 37293. however I am not 100% sure. Can someone please help !!

 

[alldodge]

Re: help with mercruiser 5.0L !

The part number you listed is a sender which sends signals to your oil pressure gauge. The gauge will not stop the engine. A serial number of your engine is needed for best results. If you don't know the serial number we at least need to know is this an EFI or carb engine?

Welcome to iboats

 

[slothman]

Re: help with mercruiser 5.0L !

It is carb, I believe the fuel pump is a manual pump. Model 0f537121 I think

 

[alldodge]

Re: help with mercruiser 5.0L !

It is carb, I believe the fuel pump is a manual pump. Model 0f537121 I think

The serial number you listed is for an Alpha 1 stren drive. It appears you have a mechanical fuel pump and with that there are no electrical issues ahich can cause the fuel pump to stop pumping.

What have you or others done this season to get the boat ready?
Was the fuel filter changed or replaced?
How old is the gas?

 

[slothman]

Re: help with mercruiser 5.0L !

The serial number you listed is for an Alpha 1 stren drive. It appears you have a mechanical fuel pump and with that there are no electrical issues ahich can cause the fuel pump to stop pumping.

What have you or others done this season to get the boat ready?
Was the fuel filter changed or replaced?
How old is the gas?

I just bought the boat as a project, mechanical maintenance unknown. I am not sure about the fuel filter, I could only locate the water separator filter. I just put in fresh fuel.

I did some more reading and it appears the tachometer might be the issue. When I crank it over, the tach bounces all over and reads 4000+ rpms, and says the same while idling. Do you think this could cause low spark, or ruin the coil? Would this cause it to shut off randomly after idling a few minutes?

I'm thinking about pulling the grey tach wire from the coil, and seeing if she fires up more quickly or holds idle without shutting off.

 

[slothman]

Re: help with mercruiser 5.0L !

update: I unplugged the grey wire from the back of the tach, still did not help the issue. I pulled the wire from the coil and cranked it over, I saw very little spark. The inside of the coil looks nasty. As well as the coil wire. Should I go ahead and buy a new coil with dist. cap and wires?

 

[Fun Times]

Re: help with mercruiser 5.0L !

update: I unplugged the grey wire from the back of the tach, still did not help the issue. I pulled the wire from the coil and cranked it over, I saw very little spark. The inside of the coil looks nasty. As well as the coil wire. Should I go ahead and buy a new coil with dist. cap and wires?

Normally you can ohms check the coil as a test, But to be honest, In real life, checking it does not always seem to tell the whole story of it's condition in my opinion. So as an alternative, testing with a new coil could be beneficial. Again in my opinion.

In the OEM service manual, There should be a test tree to follow along that covers the ignition system/no spark. It may help. Good luck.

 

[slothman]

Re: help with mercruiser 5.0L !

Normally you can ohms check the coil as a test, But to be honest, In real life, checking it does not always seem to tell the whole story of it's condition in my opinion. So as an alternative, testing with a new coil could be beneficial. Again in my opinion.

In the OEM service manual, There should be a test tree to follow along that covers the ignition system/no spark. It may help. Good luck.

I think I may just buy a new coil. But I will test the resistance first and also see how many volts it is showing. It looks like the oil has leaked because it's black and nasty inside. And the top nuts look corroded. Only God knows what the spark plugs look like, and the condition of the distributor cap. I may also pull the metal carb fuel line to make sure she is getting enough fuel.

 

[alldodge]

Re: help with mercruiser 5.0L !

I think I may just buy a new coil. But I will test the resistance first and also see how many volts it is showing. It looks like the oil has leaked because it's black and nasty inside. And the top nuts look corroded. Only God knows what the spark plugs look like, and the condition of the distributor cap. I may also pull the metal carb fuel line to make sure she is getting enough fuel.

If you buy a new coil remember you need one that uses a resistor inline. Also check the resistor

 

[slothman]

Re: help with mercruiser 5.0L !

If you buy a new coil remember you need one that uses a resistor inline. Also check the resistor

this will work, correct? http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Ignition-Coil/_/R-SME185438_0134693954

matches part # 805570A 2

 

[alldodge]

Re: help with mercruiser 5.0L !

this will work, correct? NAPA AUTO PARTS

matches part # 805570A 2

Yep, that matches up to what I found also

 

[slothman]

Re: help with mercruiser 5.0L !

Yep, that matches up to what I found also

cool, I will install new coil and plugs. Hopefully this solves the issue !

 

[slothman]

Re: help with mercruiser 5.0L !

I ordered a new coil today, so while waiting for the part I went and pulled the metal fuel line (in front of carb) to test the fuel pump. When I cranked it over for a little while not too much fuel came out. Not even a steady stream. It was more of a "gurgle" or bubbling out of the fuel line. So how much fuel should be coming from this manual fuel pump? I would assume there would be more pressure. Maybe my problem is a clogged fuel filter or clogged fuel line ?

 

[tank1949]

Re: help with mercruiser 5.0L !

Bunch! You may also have what we are all experiencing======= gasohol crap. Clogged filers, etc. Pull fuel seperator and see what dumps into a 5 gal bucket. If your 305 has manual fuel pump, it will be on stb side of block near frnt. Thing should have 3/8 fuel line going into carb. If fuel pump is electric, I didn't have much success replcing with auomotive grade pumps. It will also have a low oil pressure switch to aid in a safty feature. They do go bad and the idiot who owned my present boat before me, had it all jury rigged and unsafe. The fool had cut all switch wires for both motors going to helm alarms. Mine is a 1994 Proline with dual 350 chevy MCs. If you bought boat new, you should know history. If used, there is no telling what has been replaced. As funtime implies, get a good manual.

 

[slothman]

Re: help with mercruiser 5.0L !

Bunch! You may also have what we are all experiencing======= gasohol crap. Clogged filers, etc. Pull fuel seperator and see what dumps into a 5 gal bucket. If your 305 has manual fuel pump, it will be on stb side of block near frnt. Thing should have 3/8 fuel line going into carb. If fuel pump is electric, I didn't have much success replcing with auomotive grade pumps. It will also have a low oil pressure switch to aid in a safty feature. They do go bad and the idiot who owned my present boat before me, had it all jury rigged and unsafe. The fool had cut all switch wires for both motors going to helm alarms. Mine is a 1994 Proline with dual 350 chevy MCs. If you bought boat new, you should know history. If used, there is no telling what has been replaced. As funtime implies, get a good manual.

When I pulled the water/fuel separator, it was only 1/4 full. Should it be completely full ? It looked liked watered down gas. Could a faulty water fuel separator cause no start problems? Or do you think it's more likely the mechanical fuel pump? I was excepting the fuel to shoot out of that metal line like a rocket but it just gurgled out a little bit...

It's a 95 Reinell 18ft boat, I haven't found a regular inline fuel filter yet . Or maybe the stupid anti siphon ?!?!

 

[seilings]

Re: help with mercruiser 5.0L !

When I pulled the water/fuel separator, it was only 1/4 full. Should it be completely full ? It looked liked watered down gas. Could a faulty water fuel separator cause no start problems? Or do you think it's more likely the mechanical fuel pump? I was excepting the fuel to shoot out of that metal line like a rocket but it just gurgled out a little bit...

It's a 95 Reinell 18ft boat, I haven't found a regular inline fuel filter yet . Or maybe the stupid anti siphon ?!?!

Not sure if this help, but just let you know that last time when I replace the fuel water separator filter, it was full of fuel. (mine is 4.3 engine)

 

[alldodge]

Re: help with mercruiser 5.0L !

When I pulled the water/fuel separator, it was only 1/4 full. Should it be completely full ? It looked liked watered down gas. Could a faulty water fuel separator cause no start problems? Or do you think it's more likely the mechanical fuel pump? I was excepting the fuel to shoot out of that metal line like a rocket but it just gurgled out a little bit...

It's a 95 Reinell 18ft boat, I haven't found a regular inline fuel filter yet . Or maybe the stupid anti siphon ?!?!

Well we just went from low to no spark to no fuel. Yes, the filter should be full of gas, and it will cause a no start because the engine is not getting any gas. You probably do not have an electrical issue. Test your fuel pump, make sure all of your lines are clear. If the filter you just pulled off has not been replaced, I would suggest doing so.

 

[slothman]

Re: help with mercruiser 5.0L !

Well we just went from low to no spark to no fuel. Yes, the filter should be full of gas, and it will cause a no start because the engine is not getting any gas. You probably do not have an electrical issue. Test your fuel pump, make sure all of your lines are clear. If the filter you just pulled off has not been replaced, I would suggest doing so.

Only God knows how old the separator is lol. I will replace it. Maybe it is causing the low fuel pressure coming out of the fuel line ?

And I still think the coil is bad. I am hearing the spark, and it is intermittent .

 

[tank1949]

Re: help with mercruiser 5.0L !

Mine have always been full of something liquid.

 

[slothman]

Re: help with mercruiser 5.0L !

I replaced the separator. Filled it to the top with gas. Installed it and cranked her over. She didn't start. I pulled the separator again, and a little bit of the gas was gone. I THINK the manual fuel pump is doing its job, but I don't know if it's building adequate pressure.

I also cleaned the coil wire and cleaned the inside of the coil itself. It was goopy and full of grease. I am not sure if this is how they come from the factory. But that crap was everywhere. I pulled the wire from the coil side and left it sitting on top of the coil, and cranked her over. I didn't see a single spark, nor did I hearing any pop pop. MAYBE it's a spark issue after all, but I am still perplexed. I will have the new coil tomorrow.